Fish and shellfish farming significantly contribute to the global food supply and is a source of a major economic activity in developing nations (FAO Fisheries department, 2000). As the supply of food fish and shellfish from capture fisheries declines globally, there is an urgent need to enhance aquaculture production. The development of aquaculture in a sustainable manner faces a number of challenges. Among them diseases caused by diverse etiologic agents is of particular importance. Disease outbreaks and emergence of new pathogens poses a major challenge for sustainable development in aquaculture. A case in point is shrimp aquaculture.
During the past decade, shrimp (Penaeus sp.) farming has evolved from subsistence level farming to a major worldwide industry providing jobs to millions of people both directly and indirectly, particularly in the coastal areas of the developing nations in the Asia and the Central and South Americas. Among the challenges facing shrimp farming globally, economic losses from diseases caused by viruses are a major concern. Since the first report of a viral disease in early 1970s, more than 20 viruses have been reported that infect shrimp (Lightner, 1996, Rev. Sci. Tech. Off. Int. Epiz. 15:579-601). This list is growing rapidly. Many of shrimp viruses have caused serious epizootics in penaeid shrimp resulting in significant economic losses to commercial shrimp farmers and potentially affecting wild crustacean populations adversely. The four most important viruses of penaeid shrimp are white spot syndrome virus (WSSV), yellowhead virus (YHV), Taura syndrome virus (TSV) and the infectious hypodermal and hematopoietic necrosis virus (IHHNV). WSSV, YHV, and, more recently, TSV have caused serious epizootics in the Eastern Hemisphere; whereas, WSSV, TSV and IHHNV related economic losses have occurred in the Western Hemisphere (Dhar et al., 2004, Adv. Virus Res., In press; Tu et al., 1999, Dis. Aquat. Org. 38:159-161; Lightner et al., 1996, Rev. Sci. Tech. Off. Int. Epiz. 16:146-160). Considerable progress has been made in developing detection methods and characterizing these viral pathogens at molecular level over the last few years. However, information on the role of the virally encoded proteins in viral pathogenesis and the genes  involved in host anti-viral response remains largely unknown. This is primarily because of: (1) a lack of a suitable transient and transfection vectors for shrimp and other crustaceans and (2) a lack of a permanent cell line for shrimp and any other crustaceans.
The instant invention addresses these issues by developing expression vectors for transient expression of foreign genes, and for transfection of shrimp primary cell lines with foreign genes or modifiers of endogenous genes. These vectors could be used (1) to express recombinant protein(s) with therapeutic potential using shrimp or other crustacean host, (2) to express host gene or foreign gene in excess to determine their role in growth, development, and or disease resistance using shrimp or other crustacean host, (3) to develop a transgenic shrimp or other crustaceans, and (4) to study the role of virally encoded protein in viral pathogenesis in vitro and in vivo. These techniques will develop the tools needed to modify primary cell cultures to enable the development of unregulated growth necessary for immortalized cell lines.